Convert NaN to 0 in javascript

Question

Is there a way to convert NaN values to 0 without an if statement   if  isNaN a   a   0    It is very annoying to check my variables every time

User · Answer

x000D   x000D      var i    NaN  1 2 3        var j   i map i   gt   return isNaN i    0   i             console log j  x000D   x000D   x000D

User · Answer

Please try this simple function  var NanValue   function  entry        if entry   NaN             return 0 00        else           return entry

User · Answer

Write your own method  and use it everywhere you want a number value   function getNum val       if  isNaN val          return 0          return val

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using user 113716 solution  which by the way is great to avoid all those if-else I have implemented it this way to calculate my subtotal textbox from textbox unit and textbox quantity   In the process writing of non numbers in unit and quantity textboxes  their values are bing replace by zero so final posting of user data has no non-numbers          lt script src   common tools jquery-1 10 2 js  gt  lt  script gt        lt script src   common tools jquery-ui js  gt  lt  script gt         lt  ----------------- link above 2 lines to your jquery files ------ gt            lt script type  text javascript   gt      function calculate subtotal             quantity   val       quantity   val      0            unit   val       unit   val      0         var  calculated       quantity   val         unit   val             subtotal   val calculated                lt  script gt           lt input type    text  onChange   calculate subtotal     id    quantity   gt         lt input type    text  onChange   calculate subtotal     id    unit   gt         lt input type    text  id    subtotal   gt

User · Answer

Methods that use isNaN do not work if you re trying to use parseInt  for example   parseInt  abc       NaN parseInt         NaN parseInt  14px       14   But in the second case isNaN produces false  i e  the null string is a number   n  abc   isNaN n    0   parseInt n      0 n     isNaN n    0  parseInt n      NaN n  14px   isNaN n    0   parseInt n      14   In summary  the null string is considered a valid number by isNaN but not by parseInt  Verified with Safari  Firefox and Chrome on OSX Mojave

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How about a regex   function getNum str      return   -    0-9      0-9    test str  parseFloat str  0      The code below will ignore NaN to allow a calculation of properly entered numbers   x000D   x000D  function getNum str    x000D    return   -    0-9      0-9    test str  parseFloat str  0  x000D    x000D  var inputsArray   document getElementsByTagName  input    x000D   x000D  function computeTotal     x000D    var tot   0  x000D    tot    getNum inputsArray 0  value   x000D    tot    getNum inputsArray 1  value   x000D    tot    getNum inputsArray 2  value   x000D    inputsArray 3  value   tot  x000D    x000D   lt input type  text  gt  lt  input gt  x000D   lt input type  text  gt  lt  input gt  x000D   lt input type  text  gt  lt  input gt  x000D   lt input type  text  disabled gt  lt  input gt  x000D   lt button type  button  onclick  computeTotal    gt Calculate lt  button gt  x000D   x000D   x000D

User · Answer

You can do this   a   a    0      which will convert a from any  falsey  value to 0   The  falsey  values are    false null undefined 0      empty string   NaN   Not a Number       Or this if you prefer   a   a   a   0       which will have the same effect as above     If the intent was to test for more than just NaN  then you can do the same  but do a toNumber conversion first   a    a    0   This uses the unary   operator to try to convert a to a number  This has the added benefit of converting things like numeric strings  123  to a number   The only unexpected thing may be if someone passes an Array that can successfully be converted to a number      123       123   Here we have an Array that has a single member that is a numeric string  It will be successfully converted to a number

User · Answer

Rather than kludging it so you can continue  why not back up and wonder why you re running into a NaN in the first place   If any of the numeric inputs to an operation is NaN  the output will also be NaN  That s the way the current IEEE Floating Point standard works  it s not just Javascript   That behavior  is for a good reason  the underlying intention is to keep you from using a bogus result without realizing it s bogus    The way NaN works is if something goes wrong way down in some sub-sub-sub-operation  producing a NaN at that lower level   the final result will also be NaN  which you ll immediately recognize as an error even if your error handling logic  throw catch maybe   isn t yet complete    NaN as the result of an arithmetic calculation always indicates something has gone awry in the details of the arithmetic  It s a way for the computer to say  debugging needed here   Rather than finding some way to continue anyway with some number that s hardly ever right  is 0 really what you want    why not find the problem and fix it    A common problem in Javascript is that both parseInt      and parseFloat      will return NaN if given a nonsensical argument  null      etc   Fix the issue at the lowest level possible rather than at a higher level  Then the result of the overall calculation has a good chance of making sense  and you re not substituting some magic number  0 or 1 or whatever  for the result of the entire calculation   The trick of  parseInt foo value     0  works only for sums  not products - for products you want the default value to be 1 rather than 0  but not if the specified value really is 0    Perhaps for ease of coding you want a function to retrieve a value from the user  clean it up  and provide a default value if necessary  like this    function getFoobarFromUser elementid            var foobar   parseFloat document getElementById elementid  innerHTML          if  isNaN foobar   foobar   3 21           default value         return foobar toFixed 2

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Using a double-tilde  double bitwise NOT  -    - does some interesting things in JavaScript  For instance you can use it instead of Math floor or even as an alternative to parseInt  123   10   It s been discussed a lot over the web  so I won t go in why it works here  but if you re interested  What is the  quot double tilde quot       operator in JavaScript   We can exploit this property of a double-tilde to convert NaN to a number  and happily that number is zero   console log   NaN      0

User · Answer

Something simpler and effective for anything    function getNum val       val    val    0    return val         which will convert a from any  falsey  value to 0   The  falsey  values are    false null undefined 0      empty string   NaN   Not a Number

User · Answer

NaN is the only value in JS which is not equals to itself so we can use this information in our favour const x   NaN  let y   x  x  amp  amp  0   y   Number isNaN x   amp  amp  0  We can also use Number isNaN instead of isNaN function as latter coerces its argument to number isNaN  string             true which is incorrect because  string    string  Number isNaN  string      false

[javascript] Convert NaN to 0 in javascript

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